Allow zero as lapse in relation

api/v01/entities/vrp_input.rb

@@ -257,7 +257,7 @@ module VrpMisc
                            It could be the following types: same_route, sequence, order, minimum_day_lapse, maximum_day_lapse,
                            shipment, meetup, minimum_duration_lapse, maximum_duration_lapse')
     optional(:lapse,
-             type: Integer, values: ->(v) { v.positive? },
+             type: Integer, values: ->(v) { v >= 0 },
              desc: 'Only used for relations implying a duration constraint : minimum/maximum day lapse, vehicle group durations...')
     optional(:linked_ids, type: Array[String], allow_blank: false, desc: 'List of activities involved in the relation', coerce_with: ->(val) { val.is_a?(String) ? val.split(/,/) : val })
     optional(:linked_vehicle_ids, type: Array[String], allow_blank: false, desc: 'List of vehicles involved in the relation', coerce_with: ->(val) { val.is_a?(String) ? val.split(/,/) : val })

test/lib/interpreters/multi_trips_test.rb

@@ -115,4 +115,18 @@ def test_solve_vehicles_trips
     assert route1
     assert route0[:activities].last[:departure_time] <= route1[:activities].first[:begin_time]
   end
+
+  def test_vehicle_trips_with_lapse_0
+    problem = VRP.lat_lon_two_vehicles
+    problem[:relations] = [{
+      type: :vehicle_trips,
+      lapse: 0,
+      linked_vehicle_ids: problem[:vehicles].collect{ |v| v[:id] }
+    }]
+
+    result = OptimizerWrapper.wrapper_vrp('demo', { services: { vrp: [:ortools] }}, TestHelper.create(problem), nil)
+    first_route = result[:routes].find{ |r| r[:vehicle_id] == 'vehicle_0' }
+    second_route = result[:routes].find{ |r| r[:vehicle_id] == 'vehicle_1' }
+    assert_operator first_route[:end_time], :<=, second_route[:start_time]
+  end
 end